Re: A nice puzzle: How fast does the E field move?

From: sal (pragmatist_at_nospam.org)
Date: 08/20/04 

Date: Fri, 20 Aug 2004 13:32:16 -0400

On Fri, 20 Aug 2004 15:07:58 +0000, Androcles wrote:

>
> "suzysewnshow" <suzysewnshow@yahoo.com.au> wrote in message
> news:e0a23188.0408200552.49807fd8@posting.google.com...
> | ...
> | >
> | > > Presumably this was instantaneous
> | > > acceleration.
> | >
> | > Essentially. The length of the acceleration corresponds roughly to the
> | > thickness of the arc of "stretched" lines, that run almost
> | > tangentially rather than vertically.
> | >
> | >
> | > > Dunno where that arc comes from, though.
> | >
> | > If you mean the part that looks like the sclera of the eyeball (if
> | > this were a cross section of an eyeball instead of an electron's
> | > field), it's the "distorted" field which was produced while the
> | > particle was accelerating.
> | >
> | >
> | > > http://www.androc1es.pwp.blueyonder.co.uk/Thompson.bmp
> | >
> | > Yes, just as you show -- the lines move along with the particle, so
> | > once the shell of "dislocation" (the arc of "stretched" lines) passes
> | > an observer, that observer will see the field pointing directly toward
> | > the particle. (And that shell moves away from the particle at C.)
> | >
> | > Or, rather, the field will point to where the particle _would_ _be_ if
> it
> | > did not accelerate again -- the field _outside_ the dislocated region
> | > continues to move just as the particle did before it accelerated, and
> | > continues to point to where the particle would have been had it kept
> going
> | > that way.
> | >
> | You can put some real teeth in this POV by also looking at the radiaion
> | reaction because it is measureable. Some other illustrations:
> | http://mxp.physics.umn.edu/s04/Projects/s04cherenkov/theory.htm
>
> Diagram is a bow wave.
>
> sal begins with "They are stationary with respect to each other (and the
> aether, if any, depending on your beliefs), "
>
> and then changes horses in midstream to
>
> "If you must have an aether in relativity, then it's a movable aether. In
> this case, it is assumed to be moving _with_ _the_ _source_."
>
> I can't respond to such an obvious contradiction. Androcles.

So I accelerated, rather than keeping to uniform motion.

The first bit -- "stationary with respect to an aether" -- was an
impulsive comment, not well thought out. Strike it, please.

The later comment -- "the aether moves with the source" -- is a
description of how you must view it if you are going to insist on an
aether (like the surface of a river), and still require that you get the
result SR obtains.

If you're going to insist on an aether _and_ insist that it behave the way
Lorentz's aether (or Ken Seto's aether) would actually behave you'll have
to work out the consequences for yourself because my grasp of aether
theory isn't strong enough to allow me to do it for you.

I also haven't worked out what would happen in the case of emission
theory, because I got as far as having the expanding shell of "accelerated
field" pass an observer and realized I didn't have a clue which direction
the E field would appear to point at that moment, according to Ritz
theory. Ritz's photons are clear enough but Ritz's description of static
fields is beyond my ken.

> | http://www.physics.ubc.ca/~mattison/Courses/Phys454/lecture31.pdf
> | http://chaos.fullerton.edu/~jimw/general/radreact/ Kind regards, Sue... 

-- 
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